Photoluminescent phosphors

• US 5,039,448 A
• Filed: 06/06/1989
• Issued: 08/13/1991
• Est. Priority Date: 09/02/1983
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Ackerman, John F.
• Primary Examiner(s): Cooper, Jack
• Application Number:
  US07/363,458
• Time in Patent Office: 798 Days
• Field of Search: 252/301.4 H, 252/301.4 F
• US Class Current: 252/301.40H
• CPC Class Codes: C09K 11/665 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/675 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/88 containing selenium, tellurium or unspecified chalcogen elements
• CPC Class Codes: G21K 4/00 Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens photographic processes using X-ray intensifiers G03C5/17; discharge tubes comprising luminescent screens H01J1/62; cathode ray tubes for X-ray conversion with optical output H01J31/50
• CPC Class Codes: H04N 7/141 between two video terminals, e.g. videophone telephonic communication systems combined with television receiver for reception of entertainment or information matter H04M11/085

Abstract

An X-ray imaging system includes a phosphor that exhibits a fast-acting photoluminescent response both in luminescing upon X-ray stimulation and ceasing to luminesce upon cessation of X-ray stimulation. The phosphor has the general formula A₂ MX₆ wherein A is selected from Cs, Rb, Na and K; M is selected from Ti, Zr, Hf and Te; and X is selected from Cl and Br. In one form the phosphor has a purity with respect to naturally-occuring impurities of at least about 98.0 percent (by weight) and is sufficiently deficient of luminescent activators effective only at very low temperatures that the phosphor luminesces at higher temperatures.

Claims

1. A photoluminescent phosphor having the formula:

space="preserve" listing-type="equation">Cs.sub.2 Hf.sub.1-x Te.sub.x Cl.sub.6 or Cs.sub.2 Zr.sub.1-x Te.sub.x Cl.sub.6

wherein 0.005≦

X≦

0.1, said phosphor having a purity with respect to naturally-occurring impurities of at least about 98.0% by weight and being sufficiently deficient of luminescent activators effective only at temperatures below about 77°

Kelvin that said phosphor exhibits luminescence in response to X-ray bombardment at temperatures greater than about 77°

Kelvin.

2. The photoluminescent phosphor of claim 1 having the formula:

space="preserve" listing-type="equation">Cs.sub.2 Hf.sub.1-x Te.sub.x Cl.sub.6

wherein 0.005≦

X≦

0.1.

3. The photoluminescent phosphor of claim 1 having the formula:

space="preserve" listing-type="equation">Cs.sub.2 Zr.sub.1-x Te.sub.x Cl.sub.6

wherein 0.005≦

X≦

0.1.

4. The photoluminescent phosphor of claim 1 wherein said phosphor has a purity with respect to naturally-occurring impurities of at least about 99.5%.

5. The photoluminescent phosphor of claim 1 wherein said phosphor exhibits a luminescent spectrum comprising a single, continuous, broad emission.